The invention relates to an input and a display device provided with an output screen and means for determining a position of a pointing device relative to a position at the output screen, said means for determining comprising elongated radiation sources along two substantially non-parallel sides of the output screen for radiating radiation in beams to opposing sides of the output screen, which beams are substantially parallel to a surface of the output screen.
Such a device is known from European patent application EP-A2-0.365.232 wherein is disclosed an integrated liquid crystal display with an optical touch panel. The elongated radiation sources comprise one or several conventional light emitting diodes arranged to emit a continuous beam of light along it""s length. Additional illumination means are provided for illuminating the output screen.
It is an object of the present invention to provide an input and display device in which the generation of the light used for various purposes is simplified.
An input and display device according to the invention thereto is characterized in that a lighting system for the output screen is provided, which lighting system comprises a substantially flat light guide and in that the elongated radiation sources comprise means stretching along two substantially non-parallel end sides of the flat light guide for coupling radiation into the flat light guide, which means for coupling radiation into the flat light guide have radiation output windows with tangential dimensions larger than the thickness dimension of the flat light guide, which tangential dimensions are in a direction substantially orthogonal to a surface of the flat light guide, which surface of the flat light guide is substantially parallel to the surface of the output screen, and which means for coupling radiation into the flat light guide protrude above an upper one of said surfaces and have portions of the radiation output windows protruding above the upper one of said surfaces.
Thereby it is achieved that with a single light emitting element, such as a lamp or a light emitting diode both the lighting system for the output screen and the elongated radiation sources are provided with radiation.
A preferred embodiment of an input and a display device according to the invention is characterized in that at least one of the means for coupling radiation into the flat light guide comprises an elongated piece of the same material of which the flat light guide is comprised, which elongated piece is rotated over 90xc2x0 about a longitudinal axis of the elongated piece relative to the orientation of the flat light guide.
Thereby it is achieved that from a manufacturing point of view a single flat element can be manufactured and subsequently be cut into pieces, one larger piece forming the flat light guide and two smaller pieces forming the means for both coupling radiation into the light guide and for providing beams substantially parallel to a surface of the output screen.